Received 24 January 2013Accepted 12 March 2013Published online 10 April 2013

Acknowledgments:

We gratefully acknowledge the support of the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, the support of the National Science Foundation (NSF) through Grant No. CHE-1058791 and the National Institute of Health (Grant No. GM-59230). Help on the REW-TDDFT calculations from Niranjan Govind of the Pacific Northwest National Lab (PNNL) is greatly appreciated.